Virtual voltage injection-based speed sensor-less driving control method for induction motor

ABSTRACT

A virtual voltage injection-based speed sensor-less driving control method for an induction motor is provided. First, a virtual voltage signal is injected into a motor flux linkage and rotating speed observer so that there is a difference between an input of the motor flux linkage and rotating speed observer and a command input of the motor. Then, based on any type of the motor flux linkage and rotating speed observer, a motor flux linkage rotation angle and a motor rotor speed are estimated, and the induction motor is driven to run normally with a certain control strategy (such as vector control). Then, based on a signal designed according to this method and injected only into the motor flux linkage and rotating speed observer, the induction motor driven by a speed sensor-less control system for the induction motor may be ensured to output 150% of a rated torque when running at a motor low synchronous rotating speed and a motor zero synchronous rotating speed, and the stability thereof may be kept for a long time.

BACKGROUND OF THE INVENTION Field of the Invention

The invention belongs to the motor control field, and in particularrelates to a virtual voltage injection-based speed sensor-less drivingcontrol method for induction motor.

Description of Related Art

Induction motor (IM) is an AC motor relying on electromagnetic inductionto induce rotor current to achieve electromechanical energy conversion,and is substantially an asynchronous motor.

Motor speed detection devices mostly use speed sensors. The installationof these speed sensors increases the cost of the motor control system.In addition, speed sensors are not suitable for harsh environments suchas high humidity, vibration, and electromagnetic noise interference.Therefore, the speed sensorless technology, that is, how to quickly andaccurately estimate the rotating speed value of the motor via knownspeed control system parameters, has become another hot spot in today'sresearch. However, there are also defects in the speed sensor-lessdriving control system: the motor low-speed operation has weak loadingcapacity and instability at low-speed power generation.

In order to ensure that the speed sensor-less drive system for inductionmotor may run stably for a long time when the motor synchronous rotatingspeed is zero or the motor rotor speed is zero, many studies have beendone in recent years, mainly including low-frequency current signalinjection method, high-frequency current/voltage signal injectionmethod, rotor position estimation by detecting zero sequence currentharmonics, etc. However, the above methods require the induction motorto have significant magnetic field anisotropy, and depend on motordesign, and have issues such as torque fluctuation and noise. Noenterprise or research institution may realize the stable operation ofthe speed sensor-less drive system for induction motor at zerosynchronous rotating speed without the signal injection of the motor.

SUMMARY OF THE INVENTION

In view of the defects of the prior art, an object of the invention isto solve the technical issue of instability of the existing speedsensor-less control system for the induction motor at low synchronousrotating speed and zero synchronous rotating speed.

To achieve the above object, in a first aspect, the invention provides avirtual voltage injection-based speed sensor-less driving control methodfor induction motor, wherein in the method, based on an existing speedsensor-less drive system for induction motor, a virtual voltageinjection module is added between stator voltage command input valuesu_(sα) and u_(sβ) and flux linkage observer stator voltage input valuesu*_(sα) and u*_(sβ) of a motor in an αβ coordinate system, or a virtualvoltage injection module is added between stator voltage command inputvalues u_(sd) and u_(sq) and flux linkage observer stator voltage inputvalues u*_(sd) and u*_(sq) of the motor in a dq coordinate system, andthe method includes the following steps:

S1. k is calculated based on a parameter of an induction motor, whereink is a proportional relationship in the virtual voltage injectionmodule;

S2. The stator voltage command input values u_(sα) and u_(sβ) of themotor in the αβ coordinate system are multiplied by the proportionalrelationship k respectively to obtain the flux linkage observer statorvoltage input values u*_(sα) and u*_(sβ) in the αβ coordinate system; orthe stator voltage command input values u_(sd) and u_(sq) of the motorin the dq coordinate system are multiplied by the proportionalrelationship k respectively to obtain the flux linkage observer statorvoltage input values u*_(sd) and u*_(sq) in the dq coordinate system;

the operation is equivalent to injecting u_(sα_inj) and u_(sβ_inj) onthe basis of u_(sα) and u_(sβ), wherein

u_(s α_inj) = (k − 1)u_(s α) u_(sβ_inj) = (k − 1)u_(sβ),

to satisfy

u_(s α)^(*) = u_(s α_inj) + u_(s α) = ku_(s α)u_(sβ)^(*) = u_(sβ_inj) + u_(s β) = ku_(s β),

in the formula, u_(sα_inj) is a virtual voltage injection value under anα-axis, and u_(sβ_inj) is a virtual voltage injection value under aβ-axis;

or the operation is equivalent to injecting u_(sd_inj) and u_(sq_inj) onthe basis of u_(sd) and u_(sq), wherein

u_(s d_inj) = (k − 1)u_(s d) u_(sq_inj) = (k − 1)u_(s q),

to satisfy

u_(sd)^(*) = u_(s d_inj) + u_(s d) = ku_(sd)u_(sq)^(*) = u_(sq_inj) + u_(sq) = k u_(s q),

in the formula, u_(sd_inj) is a virtual voltage injection value under ad-axis, and u_(sq_inj) is a virtual voltage injection value under aq-axis;

S3. A dynamic mathematical model of a flux linkage observer isconstructed based on u*_(sα) and u*_(sβ) or u*_(sd) and u*_(sq);

S4. An induction motor rotor speed {circumflex over (ω)}_(r) is observedusing a rotating speed observer and a rotation angle {circumflex over(θ)} of a rotor flux linkage is observed using the flux linkage observerbased on the dynamic mathematical model of the flux linkage observer;

S5. A control of speed sensor-less induction motor rotating speed andtorque is implemented by using the observed rotor speed {circumflex over(ω)}_(r) for a rotating speed PI adjustment module and the flux linkageobserver and using the observed rotor flux linkage rotation angle{circumflex over (θ)} for a 2-phase synchronous rotationcoordinate/2-phase static coordinate conversion module;

wherein the αβ coordinate system is a 2-phase static coordinate systemand the dq coordinate system is a 2-phase synchronous rotationcoordinate system.

Specifically, the virtual voltage injection module is implemented by anadder, a multiplier, or a combination thereof.

Specifically, a calculation formula of the proportional relationship kin step S1 is as follows:

$k = {{p\frac{R_{r}L_{m}}{L_{r}}} + 1}$

wherein p is a constant greater than zero, and is obtained based on astability degree of induction motor speed and torque; R_(r) is aninduction motor rotor resistance; L_(m) is n induction motor mutualinductance; and L_(r) is an induction motor rotor side inductance.

Specifically, the dynamic mathematical model of the flux linkageobserver constructed based on u*_(sα) and u*_(sβ) in step S3 is asfollows:

$\left\{ {{{\begin{matrix}{{\frac{d}{dt}\overset{\hat{\rightarrow}}{x}} = {{A_{1}\overset{\hat{\rightarrow}}{x}} + {\overset{\rightarrow}{u}}_{s}^{*}}} \\{{\overset{\hat{\rightarrow}}{i}}_{s} = {C\; \overset{\hat{\rightarrow}}{x}}}\end{matrix}{wherein}\text{:}\mspace{14mu} \overset{\hat{\rightarrow}}{x}} = \begin{bmatrix}{\hat{\lambda}}_{s\; \alpha} & {\hat{\lambda}}_{s\; \beta} & {\hat{\lambda}}_{r\; \alpha} & {\hat{\lambda}}_{r\; \beta}\end{bmatrix}^{T}},{{\overset{\rightarrow}{u}}_{s}^{*} = \begin{bmatrix}u_{s\; \alpha}^{*} & u_{s\; \beta}^{*} & 0 & 0\end{bmatrix}^{T}},{i_{s} = {{\begin{bmatrix}i_{s\; \alpha} & i_{s\; \beta}\end{bmatrix}^{T}A_{1}} = \begin{bmatrix}a_{11} & 0 & a_{13} & 0 \\0 & a_{11} & 0 & a_{13} \\a_{31} & 0 & a_{33} & {\hat{\omega}}_{r} \\0 & a_{31} & {\hat{\omega}}_{r} & a_{33\;}\end{bmatrix}}},{C = {{\begin{bmatrix}h_{1} & 0 & h_{2} & 0 \\0 & h_{1} & 0 & h_{2}\end{bmatrix}a_{11}} = \frac{- R_{s}}{\delta \; L_{s}}}},{a_{13} = \frac{R_{s}L_{m}}{\delta L_{s}L_{r}}},{a_{31} = \frac{R_{r}L_{m}}{\delta \; L_{s}L_{r}}},{a_{33} = {{\frac{- R_{r}}{\delta \; L_{r}}h_{1}} = \frac{1}{\delta L_{5}}}},{h_{2} = \frac{- L_{m}}{\delta L_{s}L_{r}}},{\delta = {1 - \frac{L_{m}^{2}}{L_{s}L_{r}}}}} \right.$

the dynamic mathematical model of the flux linkage observer constructedbased on u*_(sd) and u*_(sq) is as follows:

$\left\{ {{{\begin{matrix}{{\frac{d}{dt}\overset{\hat{\rightarrow}}{x}} = {{A_{1}\overset{\hat{\rightarrow}}{x}} + {\overset{\rightarrow}{u}}_{s}^{*}}} \\{{\overset{\hat{\rightarrow}}{i}}_{s} = {C\; \overset{\hat{\rightarrow}}{x}}}\end{matrix}{wherein}\text{:}\mspace{14mu} \overset{\hat{\rightarrow}}{x}} = \begin{bmatrix}{\hat{\lambda}}_{s\; \alpha} & {\hat{\lambda}}_{s\; \beta} & {\hat{\lambda}}_{r\; \alpha} & {\hat{\lambda}}_{r\; \beta}\end{bmatrix}^{T}},{{\overset{\rightarrow}{u}}_{s}^{*} = \begin{bmatrix}u_{s\; \alpha}^{*} & u_{s\; \beta}^{*} & 0 & 0\end{bmatrix}^{T}},{i_{s} = {{\begin{bmatrix}i_{s\; \alpha} & i_{s\; \beta}\end{bmatrix}^{T}A_{1}} = \begin{bmatrix}a_{11} & 0 & a_{13} & 0 \\0 & a_{11} & 0 & a_{13} \\a_{31} & 0 & a_{33} & {\omega_{e} - {\hat{\omega}}_{r}} \\0 & a_{31} & {{- \omega_{e}} + {\hat{\omega}}_{r}} & a_{33\;}\end{bmatrix}}},{C = {{\begin{bmatrix}h_{1} & 0 & h_{2} & 0 \\0 & h_{1} & 0 & h_{2}\end{bmatrix}a_{11}} = \frac{- R_{s}}{\delta \; L_{s}}}},{a_{13} = \frac{R_{s}L_{m}}{\delta L_{s}L_{r}}},{a_{31} = \frac{R_{r}L_{m}}{\delta \; L_{s}L_{r}}},{a_{33} = {{\frac{- R_{r}}{\delta \; L_{r}}h_{1}} = \frac{1}{\delta L_{s}}}},{h_{2} = \frac{- L_{m}}{\delta L_{s}L_{r}}},{\delta = {1 - \frac{L_{m}^{2}}{L_{s}L_{r}}}}} \right.$

wherein {circumflex over (λ)}_(sα), {circumflex over (λ)}_(sβ),{circumflex over (λ)}_(sd), and {circumflex over (λ)}_(sq) are statorflux linkage observation values under the α-axis, the β-axis, thed-axis, and the q-axis respectively; {circumflex over (λ)}_(rα),{circumflex over (λ)}_(rβ), {circumflex over (λ)}_(rd), and {circumflexover (λ)}_(rq) are rotor flux linkage observation values under theα-axis, the f-axis, the d-axis, and the q-axis respectively; î_(sα),î_(sβ), î_(sd), and î_(sq) are stator current observation values underthe α-axis, the β-axis, the d-axis, and the q-axis respectively; ω_(e)is a synchronous rotating speed; R_(s) and R_(r) are a motor statorresistance and rotor resistance respectively; and L_(s), L_(r), andL_(m) are a motor stator side inductance, a motor rotor side inductance,and a motor mutual inductance respectively.

Specifically, when the dynamic mathematical model of the flux linkageobserver is constructed based on u*_(sα) and u*_(sβ), a calculationformula of the induction motor rotor speed {circumflex over (ω)}_(r) instep S4 is as follows:

{circumflex over (ω)}_(r) =k _(p)[(i _(sα) −î _(sα)){circumflex over(λ)}_(rβ)−(i _(sβ) −î _(sβ)){circumflex over (λ)}_(rα)]+k _(i) S ₁

when the dynamic mathematical model of the flux linkage observer isconstructed based on u*_(sd) and u*_(sq), the calculation formula of theinduction motor rotor speed {circumflex over (ω)}_(r) in step S4 is asfollows:

{circumflex over (ω)}_(r) =k _(p)[(i _(sd) −î _(sd)){circumflex over(λ)}_(rq)−(i _(sq) −î _(sq)){circumflex over (λ)}_(rd)]+k _(i) S ₂

wherein k_(p) and k_(i) are a proportional link gain and an integrallink gain of the rotating speed observer respectively; i_(sα), i_(sβ),i_(sd), and i_(sq) are stator current actual measured values under theα-axis, the β-axis, the d-axis, and the q-axis respectively; î_(sα),î_(sβ), î_(sd), and î_(sq) are stator current observation values underthe α-axis, the β-axis, the d-axis, and the q-axis respectively;{circumflex over (λ)}_(rα), {circumflex over (λ)}_(rβ), {circumflex over(λ)}_(rd), and {circumflex over (λ)}_(rq) are rotor flux linkageobservation values under the α-axis, the f-axis, the d-axis, and theq-axis respectively; and S₁ and S₂ are time integral values of[(i_(sα)−î_(sα)){circumflex over (λ)}_(rβ)−(i_(sβ)−î_(sβ)){circumflexover (λ)}_(rα)] and [(i_(sd)−î_(sd)){circumflex over(λ)}_(rq)−(i_(sq)−î_(sq)){circumflex over (λ)}_(rd)] respectively.

Specifically, when the dynamic mathematical model of the flux linkageobserver is constructed based on u*_(sα) and u*_(sβ), the calculationformula of the rotation angle {circumflex over (θ)} in step S4 is asfollows:

$\hat{\theta} = {\arctan \frac{{\hat{\Lambda}}_{r\; \beta}}{{\hat{\Lambda}}_{r\; \alpha}}}$

when the dynamic mathematical model of the flux linkage observer isconstructed based on u*_(sd) and u*_(sq) the calculation formula of therotation angle {circumflex over (θ)} in step S4 is as follows:

$\omega_{s} = {\frac{R_{r}L_{m\;}}{L_{r}\lambda_{r\; d}}i_{sq}}$θ̂ = S₃

wherein {circumflex over (λ)}_(rα), {circumflex over (λ)}_(rβ), and{circumflex over (λ)}_(rd) are the rotor flux linkage observation valuesunder the α-axis, the β-axis, and the d-axis respectively; i_(sq) is astator current actual measured value under the q-axis, ω_(s) is a sliprotating speed, R_(r) is a motor rotor resistance, L_(r) and L_(m) are amotor rotor side inductance and a motor mutual inductance respectively,and S₃ represents a time integral for ({circumflex over (ω)}_(r)+ω_(s)).

Specifically, step S5 includes the following steps:

S501, A rotating speed PI control is performed after taking a differencewith a corresponding rotating speed command ω*_(r) using the observedinduction motor rotor speed {circumflex over (ω)}_(r) as a feedbackvalue of the rotating speed PI adjustment module;

S502, The observed flux linkage rotation angle {circumflex over (θ)} isused for a coordinate conversion calculation in a 2-phase synchronousrotation coordinate/2-phase static coordinate conversion module;

S503, An output i*_(sq) of the rotating speed PI adjustment module isused as a command of a q-axis current PI adjustment module and an outputi*_(sd) of a flux linkage current command given module is used as acommand of a d-axis current PI adjustment module; induction motortwo-phase currents i_(U) and i_(V) obtained by sampling via a currentsensor is inputted to a 3-phase static coordinate/2-phase staticcoordinate conversion module, and then {right arrow over (i)}_(s) isoutputted to the 2-phase synchronous rotation coordinate/2-phase staticcoordinate conversion module, and lastly a d-axis current i_(sd) and aq-axis current i_(sq) in the 2-phase synchronous rotation coordinatesystem are obtained, and a current PI control is performed after usingthe obtained d-axis current and q-axis current as feedback values of ad-axis current PI regulator and a q-axis current PI regulatorrespectively and taking a difference with corresponding flux linkagecurrent commands i*_(sd) and i*_(sq);

S504, Outputs u_(sd) and u_(sq) of the d-axis and q-axis current PIadjustment modules are inputted to the 2-phase synchronous rotationcoordinate/2-phase static coordinate conversion module, which converts amotor input voltage command in the 2-phase synchronous rotationcoordinate system to a motor input voltage command {right arrow over(u)}_(s) in the 2-phase static coordinate system;

S505, {right arrow over (u)}_(s) is outputted to a voltage space vectorpulse width modulation module to generate a switching signal capable ofcontrolling a switching device S_(A), S_(B), S_(C), thereby achieving anobject of controlling induction motor speed and torque.

In a second aspect, an embodiment of the invention provides acomputer-readable storage medium, wherein a computer program is storedon the computer-readable storage medium, and when the computer programis executed by a processor, the virtual voltage injection-based speedsensor-less driving control method for induction motor of the firstaspect is implemented.

In general, the above technical solutions conceived by the inventionhave the following beneficial effects compared with the prior art: inthe invention, a virtual voltage injection module is added between thestator voltage command input values u_(sα) and u_(sβ) and the fluxlinkage observer stator voltage input values u*_(sα) and u*_(sβ) of themotor in the αβ coordinate system, or, a virtual voltage injectionmodule is added between the stator voltage command input values u_(sd)and u_(sq) and the flux observer stator voltage input values u*_(sd) andu*_(sq) of the motor in the dq coordinate system, thereby achieving:

(1) Without signal injection into the motor body, an induction motorcontrolled by the speed sensor-less induction motor drive system andoutputting 150% of motor rated torque at zero synchronous rotating speedor low synchronous rotating speed may be realized.

(2) Without signal injection into the motor body, an induction motorcontrolled by the speed sensor-less induction motor drive system andrunning stably for a long time at 0% motor rated torque and zero rotorspeed and starting normally after running for a long time may berealized.

(3) Without signal injection into the motor body, an induction motorcontrolled by the speed sensor-less induction motor drive system andswitching between forward and reverse rotation of motor speed at anyacceleration and deceleration time under the condition that the load is150% of the motor rated torque without change may be realized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a structural diagram of a speed sensor-less induction motordriving control system based on virtual voltage injection provided byembodiment 1 of the invention.

FIG. 2 is a structural diagram of a speed sensor-less induction motordriving control system based on virtual voltage injection provided byembodiment 2 of the invention.

FIG. 3 is a graph of an induction motor rotor speed performance atdifferent stages provided by an embodiment of the invention.

FIG. 4 is a graph showing the change of motor U-phase stator current andmotor rotor speed command value with time provided by an embodiment ofthe invention.

DESCRIPTION OF THE EMBODIMENTS

In order to make the objects, technical solutions, and advantages of theinvention clearer, the invention is further described in detail below inconjunction with the accompanying figures and embodiments. It should beunderstood that the specific embodiments described herein are only usedto explain the invention, and are not intended to limit the invention.

FIG. 1 is a structural diagram of a i speed sensor-less driving controlfor induction motor based on virtual voltage injection provided byembodiment 1 of the invention.

The hardware part of the speed sensor-less drive system for inductionmotor includes: a three-phase voltage source inverter and an inductionmotor. A three-phase AC power obtains a DC bus voltage U_(DC) viauncontrolled rectification, which is supplied to a voltage sourceinverter, and the induction motor is controlled using an inverter tocontrol torque and rotating speed. The three-phase voltage sourceinverter includes voltage and current sensors.

The software part of the speed sensor-less drive system for inductionmotor includes: a 3-phase static coordinate/2-phase static coordinateconversion module, a 2-phase synchronous rotation coordinate/2-phasestatic coordinate conversion module, a voltage space vector pulse widthmodulation module, a current PI (proportion integration) adjustmentmodule, a rotating speed PI adjustment module, a flux linkage currentcommand given module, a rotating speed command given module, a fluxlinkage and rotating speed observer module, and a virtual voltageinjection module.

The control method of the induction motor is mainly divided into VFcontrol, vector control, and direct torque control, and the vectorcontrol strategy is preferred in the embodiments of the invention. Theinvention mainly relates to a virtual voltage injection module, and theother modules are functional modules of speed sensor-less inductionmotor vector control, which is common knowledge in the art. The virtualvoltage injection module is implemented by an adder, a multiplier, or acombination thereof.

Embodiment 1 The control system is implemented by adding a virtualvoltage injection module between stator voltage command input valuesu_(sα) and u_(sβ) and flux linkage observer stator voltage input valuesu*_(sα) and u*_(sβ) of the motor in an αβ coordinate system. Thefollowing describes the control method of the entire system, includingstep S1 to step S5.

S1. k is calculated based on a parameter of an induction motor, whereink is a proportional relationship in the virtual voltage injectionmodule. The calculation formula is as follows:

$k = {{p\frac{R_{r}L_{m}}{L_{r}}} + 1}$

wherein p is a constant greater than zero, and is obtained based on astability degree of induction motor speed and torque; R_(r) is inductionmotor rotor resistance; L_(m) is induction motor mutual inductance; andL_(r) is induction motor rotor side inductance.

After the proportional relationship k is calculated, it exists as aconstant in the motor controller, and the value thereof does not changewith each motor parameter.

S2. The stator voltage command input values u_(sα) and u_(sβ) of themotor in the αβ coordinate system are multiplied by the proportionalrelationship k respectively, to obtain the flux linkage observer statorvoltage input values u*_(sα) and u*_(sβ) in the αβ coordinate system;

the operation is equivalent to injecting u_(sα_inj) and u_(sβ_inj) onthe basis of u_(sα) and u_(sβ), wherein

u_(s α_inj) = (k − 1)u_(s α) u_(sβ_inj) = (k − 1)u_(sβ),

to satisfy

u_(s α)^(*) = u_(s α_inj) + u_(s α) = ku_(s α)u_(sβ)^(*) = u_(sβ_inj) + u_(s β) = ku_(s β),

in the formula, u_(sα_inj) is a virtual voltage injection value under anα-axis, and u_(sβ_inj) is a virtual voltage injection value under aβ-axis;

S3. A dynamic mathematical model of a flux linkage observer isconstructed based on u*_(sα) and u*_(sβ). The dynamic mathematical modelis as follows:

$\left\{ {{{\begin{matrix}{{\frac{d}{dt}\hat{\overset{\rightarrow}{x}}} = {{A_{1}\hat{\overset{\rightarrow}{x}}} + {\overset{\rightarrow}{u}}_{s}^{*}}} \\{{\hat{\overset{\rightarrow}{i}}}_{s} = {C\; \hat{\overset{\rightarrow}{x}}}}\end{matrix}{{wherein}:\hat{\overset{\rightarrow}{x}}}} = \begin{bmatrix}{\hat{\lambda}}_{s\; \alpha} & {\hat{\lambda}}_{s\; \beta} & {\hat{\lambda}}_{r\; \alpha} & {\hat{\lambda}}_{r\; \beta}\end{bmatrix}^{T}},{{\overset{\rightarrow}{u}}_{s}^{*} = \begin{bmatrix}u_{s\; \alpha}^{*} & u_{s\; \beta}^{*} & 0 & 0\end{bmatrix}^{T}},{{\hat{\overset{\rightarrow}{i}}}_{s} = \begin{bmatrix}{\hat{i}}_{s\; \alpha} & {\hat{i}}_{s\; \beta}\end{bmatrix}^{T}},{A_{1} = \begin{bmatrix}a_{11} & 0 & a_{13} & 0 \\0 & a_{11} & 0 & a_{13} \\a_{31} & 0 & a_{33} & {- {\hat{\omega}}_{r}} \\0 & a_{31} & {\hat{\omega}}_{r} & a_{33}\end{bmatrix}},{C = {{\begin{bmatrix}h_{1} & 0 & h_{2} & 0 \\0 & h_{1} & 0 & h_{2}\end{bmatrix}a_{11}} = \frac{- R_{s}}{\delta \; L_{s}}}},{a_{13} = \frac{R_{s}L_{m}}{\delta \; L_{s}L_{r}}},{a_{31} = \frac{R_{r}L_{m}}{\delta \; L_{s}L_{r}}},{a_{33} = {{\frac{- R_{r}}{\delta \; L_{r}}h_{1}} = \frac{1}{\delta \; L_{s}}}},{h_{2} = \frac{- L_{m}}{\delta \; L_{s}L_{r}}},{\delta = {1 - \frac{L_{m}^{2}}{L_{s}L_{r}}}}} \right.$

wherein {circumflex over (λ)}_(sα) and {circumflex over (λ)}_(sβ) arestator flux linkage observation values under the α-axis and the β-axisrespectively; {circumflex over (λ)}_(rα) and {circumflex over (λ)}_(rβ)are rotor flux linkage observation values under the α-axis and theβ-axis respectively; î_(sα) and î_(sβ) are stator current observationvalues under the α-axis and the β-axis respectively; R_(s) and R_(r) aremotor stator current and rotor resistance respectively; L_(s), L_(r),and L_(m) are motor stator side inductance, motor rotor side inductance,and motor mutual inductance respectively.

S4. An induction motor rotor speed {circumflex over (ω)}_(r) is observedusing a rotating speed observer and a rotation angle {circumflex over(θ)} of a rotor flux linkage is observed using the flux linkage observerbased on the dynamic mathematical model of the flux linkage observer;

${\hat{\omega}}_{r} = {{k_{p}\left\lbrack {{\left( {i_{s\; \alpha} - {\overset{\hat{}}{i}}_{s\; \alpha}} \right){\hat{\lambda}}_{r\; \beta}} - {\left( {i_{s\; \beta} - {\overset{\hat{}}{i}}_{s\; \beta}} \right){\hat{\lambda}}_{r\; \alpha}}} \right\rbrack} + {k_{i}S_{1}}}$$\overset{\hat{}}{\theta} = {\arctan \frac{{\hat{\lambda}}_{r\; \beta}}{{\hat{\lambda}}_{r\; \alpha}}}$

wherein k_(p) and k_(i) are proportional link gain and integral linkgain of the rotating speed observer respectively; i_(sα) and i_(sβ) arestator current actual measured values under the α-axis and the β-axisrespectively; î_(sα) and î_(sβ) are stator current observation valuesunder the α-axis and the β-axis respectively; {circumflex over (λ)}_(rα)and {circumflex over (λ)}_(rβ) are rotor flux linkage observation valuesunder the α-axis and the β-axis respectively; and S₁ is a time integralvalue of [(i_(sα)−î_(sα)){circumflex over(λ)}_(rβ)−(i_(sβ)−î_(sβ)){circumflex over (λ)}_(rα)].

S5. A control of speed sensor-less induction motor rotating speed andtorque is implemented by using the observed rotor speed {circumflex over(ω)}_(r) for a rotating speed PI adjustment module and the flux linkageobserver and using the observed rotor flux linkage rotation angle{circumflex over (θ)} for the 2-phase synchronous rotationcoordinate/2-phase static coordinate conversion module.

Specifically, step S5 includes the following steps:

S501, A rotating speed PI control is performed after taking a differencewith a corresponding rotating speed command {circumflex over (ω)}_(r)using the observed induction motor rotor speed {circumflex over (ω)}_(r)as a feedback value of the rotating speed PI adjustment module;

S502, The observed flux linkage rotation angle {circumflex over (θ)} isused for a coordinate conversion calculation in the 2-phase synchronousrotation coordinate/2-phase static coordinate conversion module;

S503, An output i*_(sq) of the rotating speed PI adjustment module isused as a command of a q-axis current PI adjustment module and an outputi*_(sd) of a flux linkage current command given module is used as acommand of a d-axis current PI adjustment module; induction motortwo-phase currents i_(U) and i_(V) obtained by sampling via a currentsensor is inputted to a 3-phase static coordinate/2-phase staticcoordinate conversion module, and then {right arrow over (i)}_(s) isoutputted to the 2-phase synchronous rotation coordinate/2-phase staticcoordinate conversion module, and lastly a d-axis current i_(sd) and aq-axis current i_(sq) in the 2-phase synchronous rotation coordinatesystem are obtained, and a current PI control is performed after usingthe obtained d-axis current and q-axis current as feedback values of ad-axis current PI regulator and a q-axis current PI regulatorrespectively and taking a difference with corresponding flux linkagecurrent commands i*_(sd) and i*_(sq);

S504, Outputs u_(sd) and u_(sq) of the d-axis and q-axis current PIadjustment modules are inputted to the 2-phase synchronous rotationcoordinate/2-phase static coordinate conversion module, which converts amotor input voltage command in the 2-phase synchronous rotationcoordinate system to a motor input voltage command {right arrow over(u)}_(s) in the 2-phase static coordinate system;

S505, {right arrow over (u)}_(s), is outputted to a voltage space vectorpulse width modulation module to generate a switching signal capable ofcontrolling a switching device S_(A), S_(B), S_(C), thereby achieving anobject of controlling induction motor speed and torque.

As shown in FIG. 2, Embodiment 2 The control system is implemented byadding a virtual voltage injection module between the stator voltagecommand input values u_(sd) and u_(sq) and the flux linkage observerstator voltage input values u*_(sd) and u*_(sq) of the motor in the dqcoordinate system. The following describes the control method of theentire system, including step S1 to step S5.

S1. k is calculated based on a parameter of an induction motor, whereink is a proportional relationship in the virtual voltage injectionmodule. The calculation formula is as follows:

$k = {{p\frac{R_{r}L_{m}}{L_{r}}} + 1}$

S2. The stator voltage command input values u_(sd) and u_(sq) of themotor in the dq coordinate system are multiplied by the proportionalrelationship k respectively, to obtain the flux linkage observer statorvoltage input values u*_(sd) and u*_(sq) in the dq coordinate system;

the operation is equivalent to injecting u_(sd_inj) and u_(sq_inj) onthe basis of u_(sd) and u_(sd), wherein

u_(s d_inj) = (k − 1)u_(s d) u_(sq_inj) = (k − 1)u_(s q),

to satisfy

u_(sd)^(*) = u_(s d_inj) + u_(s d) = ku_(sd)u_(sq)^(*) = u_(sq_inj) + u_(sq) = k u_(s q),

in the formula, u_(sd_inj) is a virtual voltage injection value underthe d-axis, and u_(sq_inj) is a virtual voltage injection value underthe q-axis;

S3. A dynamic mathematical model of the flux linkage observer isconstructed based on u*_(sd) and u*_(sq). The dynamic mathematical modelis as follows:

$\left\{ {{{\begin{matrix}{{\frac{d}{dt}\hat{\overset{\rightarrow}{x}}} = {{A_{2}\hat{\overset{\rightarrow}{x}}} + {\overset{\rightarrow}{u}}_{s}^{*}}} \\{{\hat{\overset{\rightarrow}{i}}}_{s} = {C\; \hat{\overset{\rightarrow}{x}}}}\end{matrix}{{wherein}:\hat{\overset{\rightarrow}{x}}}} = \begin{bmatrix}{\hat{\lambda}}_{sd} & {\hat{\lambda}}_{sq} & {\hat{\lambda}}_{r\; d} & {\hat{\lambda}}_{rq}\end{bmatrix}^{T}},{{\overset{\rightarrow}{u}}_{s}^{*} = \begin{bmatrix}u_{sd}^{*} & u_{sq}^{*} & 0 & 0\end{bmatrix}^{T}},{{\hat{\overset{\rightarrow}{i}}}_{s} = \begin{bmatrix}{\hat{i}}_{sd} & {\hat{i}}_{sq}\end{bmatrix}^{T}},{A_{1} = \begin{bmatrix}a_{11} & \omega_{e} & a_{13} & 0 \\{- \omega_{e}} & a_{11} & 0 & a_{13} \\a_{31} & 0 & a_{33} & {\omega_{e} - {\hat{\omega}}_{r}} \\0 & a_{31} & {{- \omega_{e}} + {\hat{\omega}}_{r}} & a_{33}\end{bmatrix}},{C = {{\begin{bmatrix}h_{1} & 0 & h_{2} & 0 \\0 & h_{1} & 0 & h_{2}\end{bmatrix}a_{11}} = \frac{- R_{s}}{\delta \; L_{s}}}},{a_{13} = \frac{R_{s}L_{m}}{\delta \; L_{s}L_{r}}},{a_{31} = \frac{R_{r}L_{m}}{\delta \; L_{s}L_{r}}},{a_{33} = {{\frac{- R_{r}}{\delta \; L_{r}}h_{1}} = \frac{1}{\delta \; L_{s}}}},{h_{2} = \frac{- L_{m}}{\delta \; L_{s}L_{r}}},{\delta = {1 - \frac{L_{m}^{2}}{L_{s}L_{r}}}}} \right.$

wherein {circumflex over (λ)}_(sd) and {circumflex over (λ)}_(sq) arestator flux linkage observation values under the d-axis and the q-axisrespectively; {circumflex over (λ)}_(rd) and {circumflex over (λ)}_(rq)are rotor flux linkage observation values under the d-axis and theq-axis respectively; î_(sd) and î_(sq) are stator current observationvalues under the d-axis and the q-axis respectively; ω_(e) issynchronous rotating speed; R_(s) and R_(r) are motor stator resistanceand rotor resistance respectively; L_(s), L_(r), and L_(m) are motorstator side inductance, motor rotor side inductance, and motor mutualinductance respectively.

S4. An induction motor rotor speed {circumflex over (ω)}_(r) is observedusing a rotating speed observer and a rotation angle {circumflex over(θ)} of the rotor flux linkage is observed using the flux linkageobserver based on the dynamic mathematical model of the flux linkageobserver;

${\hat{\omega}}_{r} = {{k_{p}\left\lbrack {{\left( {i_{sd} - {\overset{\hat{}}{i}}_{sd}} \right){\hat{\lambda}}_{rq}} - {\left( {i_{sq} - {\overset{\hat{}}{i}}_{sq}} \right){\hat{\lambda}}_{r\; d}}} \right\rbrack} + {k_{i}S_{2}}}$$\omega_{s} = {\frac{R_{r}L_{m}}{L_{r}{\hat{\lambda}}_{r\; d}}i_{qs}}$θ̂ = S₃

wherein k_(p) and k_(i) are proportional link gain and the integral linkgain of the rotating speed observer respectively; i_(sd) and i_(sq) arestator current actual measured values under d-axis and q-axisrespectively; î_(sd) and î_(sq) are stator current observation valuesunder d-axis and q-axis respectively; {circumflex over (λ)}_(rd) and{circumflex over (λ)}_(rq) are rotor flux linkage observation valuesunder the d-axis and q-axis respectively; S₂ is the time integral valueof [(i_(sd)−î_(sd)){circumflex over (λ)}_(rq)−(i_(sq)−î_(sq)){circumflexover (λ)}_(rd)], i_(sq) is the stator current actual measured valueunder the q-axis, ω_(s) is slip rotating speed, R_(r) is motor rotorresistance, L_(r) and L_(m) are motor rotor side inductance and motormutual inductance respectively, and S₃ represents the time integral for({circumflex over (ω)}_(r)+ω_(s)).

S5. A control of speed sensor-less induction motor rotating speed andtorque is implemented by using the observed rotor speed {circumflex over(ω)}_(r) for a rotating speed PI adjustment module and the flux linkageobserver and using the observed rotor flux linkage rotation angle{circumflex over (θ)} for the 2-phase synchronous rotationcoordinate/2-phase static coordinate conversion module.

S501, A rotating speed PI control is performed after taking a differencewith a corresponding rotating speed command ω*_(r) using the observedinduction motor rotor speed {circumflex over (ω)}_(r) as a feedbackvalue of the rotating speed PI adjustment module;

S502, The observed flux linkage rotation angle {circumflex over (θ)} isused for a coordinate conversion calculation in the 2-phase synchronousrotation coordinate/2-phase static coordinate conversion module;

S503, An output i*_(sq) of the rotating speed PI adjustment module isused as a command of a q-axis current PI adjustment module and an outputi*_(sd) of a flux linkage current command given module is used as acommand of a d-axis current PI adjustment module; induction motortwo-phase currents i_(U) and i_(V) obtained by sampling via a currentsensor is inputted to a 3-phase static coordinate/2-phase staticcoordinate conversion module, and then {right arrow over (i)}_(s) isoutputted to the 2-phase synchronous rotation coordinate/2-phase staticcoordinate conversion module, and lastly a d-axis current i_(sd) and aq-axis current i_(sq) in the 2-phase synchronous rotation coordinatesystem are obtained, and a current PI control is performed after usingthe obtained d-axis current and q-axis current as feedback values of ad-axis current PI regulator and a q-axis current PI regulatorrespectively and taking a difference with corresponding flux linkagecurrent commands i*_(sd) and i*_(sq);

S504, The outputs u_(sd) and u_(sq) of the d-axis and q-axis current PIadjustment modules are inputted to the 2-phase synchronous rotationcoordinate/2-phase static coordinate conversion module, which converts amotor input voltage command in the 2-phase synchronous rotationcoordinate system to a motor input voltage command {right arrow over(u)}_(s) in the 2-phase static coordinate system;

S505, {right arrow over (u)}_(s) is outputted to a voltage space vectorpulse width modulation module to generate a switching signal capable ofcontrolling a switching device S_(A), S_(B), S_(C), thereby achieving anobject of controlling induction motor speed and torque.

FIG. 3 is a graph of induction motor rotor speed performance atdifferent stages provided by an embodiment of the invention.

As shown in FIG. 3, the motor rotor speed may be kept stable at motorzero synchronous rotating speed and 0% load torque, zero synchronousrotating speed and 150% load torque, and low synchronous rotating speedand 150% load torque.

FIG. 4 is a graph showing the change of motor U-phase stator current andmotor rotor speed value with time provided by an embodiment of theinvention.

As shown in FIG. 4, at 150% load torque, the motor rotor speed may bekept stable when crossing from −120 rpm to 120 rpm.

The above are only preferred specific implementations of the presentapplication, but the scope of the present application is not limitedthereto, and any change or replacement within the technical scopedisclosed in this application that may be easily conceived by thoseskilled in the art shall be within the scope of the application.Therefore, the scope of the present application should be based on thescope of the claims.

1. A virtual voltage injection-based speed sensor-less driving controlmethod for induction motor, wherein in the method, based on an existingspeed sensor-less drive system for induction motor, a virtual voltageinjection module is added between stator voltage command input valuesu_(sα) and u_(sβ) and flux linkage observer stator voltage input valuesu*_(sα) and u*_(sβ) of a motor in an αβ coordinate system, or a virtualvoltage injection module is added between stator voltage command inputvalues u_(sd) and u_(sq) and flux linkage observer stator voltage inputvalues u*_(sd) and u*_(sq) of the motor in a dq coordinate system, andthe method comprises the following steps: S1. calculating k based on aparameter of an induction motor, wherein k is a proportionalrelationship in the virtual voltage injection module; S2. multiplyingthe stator voltage command input values u_(sα) and u_(sβ) of the motorin the αβ coordinate system by the proportional relationship krespectively to obtain the flux linkage observer stator voltage inputvalues u*_(sα) and u*_(sβ) in the αβ coordinate system; or multiplyingthe stator voltage command input values u_(sd) and u_(sq) of the motorin the dq coordinate system by the proportional relationship krespectively to obtain the flux linkage observer stator voltage inputvalues u and u in the dq coordinate system; the operation is equivalentto injecting u_(sα_inj) and u_(sβ_inj) on the basis of u_(sα) andu_(sβ), wherein u_(s α_inj) = (k − 1)u_(s α)u_(sβ_inj) = (k − 1)u_(sβ), to satisfyu_(s α)^(*) = u_(s α_inj) + u_(s α) = ku_(s α)u_(sβ)^(*) = u_(sβ_inj) + u_(s β) = ku_(s β), in the formula,u_(sα_inj) is a virtual voltage injection value under an α-axis, andu_(sβ_inj) is a virtual voltage injection value under a β-axis; or theoperation is equivalent to injecting u_(sd_inj) and u_(sq_inj) on thebasis of u_(sd) and u_(sq), wherein u_(s d_inj) = (k − 1)u_(s d)u_(sq_inj) = (k − 1)u_(s q), to satisfyu_(sd)^(*) = u_(s d_inj) + u_(s d) = ku_(sd)u_(sq)^(*) = u_(sq_inj) + u_(sq) = k u_(s q), in the formula,u_(sd_inj) is a virtual voltage injection value under a d-axis, andu_(sq_inj) is a virtual voltage injection value under a q-axis; S3.constructing a dynamic mathematical model of a flux linkage observerbased on u*_(sα) and u*_(sβ) or u*_(sd) and u*_(sq); S4. observing aninduction motor rotor speed {circumflex over (ω)}_(r) using a rotatingspeed observer and observing a rotation angle {circumflex over (θ)} of arotor flux linkage using the flux linkage observer based on the dynamicmathematical model of the flux linkage observer; S5. implementing acontrol of speed sensor-less induction motor rotating speed and torqueby using the observed rotor speed {circumflex over (ω)}_(r) for arotating speed PI adjustment module and the flux linkage observer andusing the observed rotor flux linkage rotation angle {circumflex over(θ)} for a 2-phase synchronous rotation coordinate/2-phase staticcoordinate conversion module; wherein the αβ coordinate system is a2-phase static coordinate system and the dq coordinate system is a2-phase synchronous rotation coordinate system.
 2. The driving controlmethod of claim 1, wherein the virtual voltage injection module isimplemented by an adder, a multiplier, or a combination thereof.
 3. Thedriving control method of claim 1, wherein a calculation formula of theproportional relationship k in step S1 is as follows:$k = {{p\frac{R_{r}L_{m}}{L_{r}}} + 1}$ wherein p is a constantgreater than zero, and is obtained based on the rated parameters ofinduction motor; R_(r) is an induction motor rotor resistance; L_(m) isan induction motor mutual inductance; and L_(r) is an induction motorrotor side inductance.
 4. The driving control method of claim 1, whereinthe dynamic mathematical model of the flux linkage observer constructedbased on u*_(sα) and u*_(sβ) in step S3 is as follows:$\left\{ {{{\begin{matrix}{{\frac{d}{dt}\hat{\overset{\rightarrow}{x}}} = {{A_{1}\hat{\overset{\rightarrow}{x}}} + {\overset{\rightarrow}{u}}_{s}^{*}}} \\{{\hat{\overset{\rightarrow}{i}}}_{s} = {C\; \hat{\overset{\rightarrow}{x}}}}\end{matrix}{{wherein}:\hat{\overset{\rightarrow}{x}}}} = \begin{bmatrix}{\hat{\lambda}}_{s\; \alpha} & {\hat{\lambda}}_{s\; \beta} & {\hat{\lambda}}_{r\; \alpha} & {\hat{\lambda}}_{r\; \beta}\end{bmatrix}^{T}},{{\overset{\rightarrow}{u}}_{s}^{*} = \begin{bmatrix}u_{s\; \alpha}^{*} & u_{s\; \beta}^{*} & 0 & 0\end{bmatrix}^{T}},{{\hat{\overset{\rightarrow}{i}}}_{s} = \begin{bmatrix}{\hat{i}}_{s\; \alpha} & {\hat{i}}_{s\; \beta}\end{bmatrix}^{T}},{A_{1} = \begin{bmatrix}a_{11} & 0 & a_{13} & 0 \\0 & a_{11} & 0 & a_{13} \\a_{31} & 0 & a_{33} & {- {\hat{\omega}}_{r}} \\0 & a_{31} & {\hat{\omega}}_{r} & a_{33}\end{bmatrix}},{C = {{\begin{bmatrix}h_{1} & 0 & h_{2} & 0 \\0 & h_{1} & 0 & h_{2}\end{bmatrix}a_{11}} = \frac{- R_{s}}{\delta \; L_{s}}}},{a_{13} = \frac{R_{s}L_{m}}{\delta \; L_{s}L_{r}}},{a_{31} = \frac{R_{r}L_{m}}{\delta \; L_{s}L_{r}}},{a_{33} = {{\frac{- R_{r}}{\delta \; L_{r}}h_{1}} = \frac{1}{\delta \; L_{s}}}},{h_{2} = \frac{- L_{m}}{\delta \; L_{s}L_{r}}},{\delta = {1 - \frac{L_{m}^{2}}{L_{s}L_{r}}}}} \right.$the dynamic mathematical model of the flux linkage observer constructedbased on u*_(sd) and u*_(sq) is as follows: $\left\{ {{{\begin{matrix}{{\frac{d}{dt}\hat{\overset{\rightarrow}{x}}} = {{A_{2}\hat{\overset{\rightarrow}{x}}} + {\overset{\rightarrow}{u}}_{s}^{*}}} \\{{\hat{\overset{\rightarrow}{i}}}_{s} = {C\; \hat{\overset{\rightarrow}{x}}}}\end{matrix}{{wherein}:\hat{\overset{\rightarrow}{x}}}} = \begin{bmatrix}{\hat{\lambda}}_{sd} & {\hat{\lambda}}_{sq} & {\hat{\lambda}}_{r\; d} & {\hat{\lambda}}_{rq}\end{bmatrix}^{T}},{{\overset{\rightarrow}{u}}_{s}^{*} = \begin{bmatrix}u_{sd}^{*} & u_{sq}^{*} & 0 & 0\end{bmatrix}^{T}},{{\hat{\overset{\rightarrow}{i}}}_{s} = \begin{bmatrix}{\hat{i}}_{sd} & {\hat{i}}_{sq}\end{bmatrix}^{T}},{A_{1} = \begin{bmatrix}a_{11} & \omega_{e} & a_{13} & 0 \\{- \omega_{e}} & a_{11} & 0 & a_{13} \\a_{31} & 0 & a_{33} & {\omega_{e} - {\hat{\omega}}_{r}} \\0 & a_{31} & {{- \omega_{e}} + {\hat{\omega}}_{r}} & a_{33}\end{bmatrix}},{C = {{\begin{bmatrix}h_{1} & 0 & h_{2} & 0 \\0 & h_{1} & 0 & h_{2}\end{bmatrix}a_{11}} = \frac{- R_{s}}{\delta \; L_{s}}}},{a_{13} = \frac{R_{s}L_{m}}{\delta \; L_{s}L_{r}}},{a_{31} = \frac{R_{r}L_{m}}{\delta \; L_{s}L_{r}}},{a_{33} = {{\frac{- R_{r}}{\delta \; L_{r}}h_{1}} = \frac{1}{\delta \; L_{s}}}},{h_{2} = \frac{- L_{m}}{\delta \; L_{s}L_{r}}},{\delta = {1 - \frac{L_{m}^{2}}{L_{s}L_{r}}}}} \right.$wherein {circumflex over (λ)}_(sα), {circumflex over (λ)}_(sβ),{circumflex over (λ)}_(sd), and {circumflex over (λ)}_(sq) are statorflux linkage observation values under the α-axis, the β-axis, thed-axis, and the q-axis respectively; {circumflex over (λ)}_(rα),{circumflex over (λ)}_(rβ), {circumflex over (λ)}_(rd), and {circumflexover (λ)}_(rq) are rotor flux linkage observation values under theα-axis, the β-axis, the d-axis, and the q-axis respectively; î_(sα),î_(sβ), î_(sd), and î_(sq) are stator current observation values underthe α-axis, the β-axis, the d-axis, and the q-axis respectively; Weisasynchronous rotating speed; R_(s) and R_(r) are a motor statorresistance and rotor resistance respectively; L_(s), L_(r), and L_(m)are a motor stator side inductance, a motor rotor side inductance, and amotor mutual inductance respectively.
 5. The driving control method ofclaim 1, wherein when the dynamic mathematical model of the flux linkageobserver is constructed based on u*_(sα) and u*_(sβ), a calculationformula of the induction motor rotor speed {circumflex over (ω)}_(r) instep S4 is as follows:{circumflex over (ω)}_(r) =k _(p)[(i _(sα) −î _(sα)){circumflex over(λ)}_(rβ)−(i _(sβ) −î _(sβ)){circumflex over (λ)}_(rα)]+k _(i) S ₁ whenthe dynamic mathematical model of the flux linkage observer isconstructed based on u*_(sd) and u*_(sq), the calculation formula of theinduction motor rotor speed {circumflex over (ω)}_(r) in step S4 is asfollows:{circumflex over (ω)}_(r) =k _(p)[(i _(sd) −î _(sd)){circumflex over(λ)}_(rq)−(i _(sq) −î _(sq)){circumflex over (λ)}_(rd)]+k _(i) S ₂wherein k_(p) and k_(i) are a proportional link gain and an integrallink gain of the rotating speed observer respectively; i_(sα), i_(sβ),i_(sd), and i_(sq) are stator current actual measured values under theα-axis, the β-axis, the d-axis, and the q-axis respectively; î_(sα),î_(sβ), î_(sd), and î_(sq) are stator current observation values underthe α-axis, the β-axis, the d-axis, and the q-axis respectively;{circumflex over (λ)}_(rα), {circumflex over (λ)}_(rβ), {circumflex over(λ)}_(rd), and {circumflex over (λ)}_(rq) are rotor flux linkageobservation values under the α-axis, the f-axis, the d-axis, and theq-axis respectively; and S₁ and S₂ are time integral values of[(i_(sα)−î_(sα)){circumflex over (λ)}_(rβ)−(i_(sβ)−î_(sβ)){circumflexover (λ)}_(rα)] and [(i_(sd)−î_(sd)){circumflex over(λ)}_(rq)−(i_(sq)−î_(sq)){circumflex over (λ)}_(rd)] respectively. 6.The driving control method of claim 1, wherein when the dynamicmathematical model of the flux linkage observer is constructed based onu*_(sα) and u*_(sβ), a calculation formula of the rotation angle{circumflex over (θ)} in step S4 is as follows:$\overset{\hat{}}{\theta} = {\arctan \frac{{\overset{\hat{}}{\lambda}}_{r\beta}}{{\hat{\lambda}}_{r\; \alpha}}}$when the dynamic mathematical model of the flux linkage observer isconstructed based on u*_(sd) and u*_(sq), the calculation formula of therotation angle {circumflex over (θ)} in step S4 is as follows:$\omega_{s} = {\frac{R_{r}L_{m}}{L_{r}{\hat{\lambda}}_{r\; d}}i_{sq}}$$\overset{\hat{}}{\theta} = S_{3}$ wherein {circumflex over (λ)}_(rα),{circumflex over (λ)}_(rβ), and {circumflex over (λ)}_(rd) are rotorflux linkage observation values under the α-axis, the β-axis, and thed-axis respectively; i_(sq) is a stator current actual measured valueunder the q-axis, ω_(s) is a slip rotating speed, R_(r) is a motor rotorresistance, L_(r) and L_(m) are a motor rotor side inductance and amotor mutual inductance respectively, and S₃ represents a time integralfor ({circumflex over (ω)}_(r)+ωs).
 7. The driving control method ofclaim 1, wherein step S5 comprises the following steps: S501, performinga rotating speed PI control after taking a difference with acorresponding rotating speed command ω*_(r) using the observed inductionmotor rotor speed {circumflex over (ω)}_(r) as a feedback value of therotating speed PI adjustment module; S502, using the observed fluxlinkage rotation angle {circumflex over (θ)} for a coordinate conversioncalculation in a 2-phase synchronous rotation coordinate/2-phase staticcoordinate conversion module; S503, using an output i*_(sq) of therotating speed PI adjustment module as a command of a q-axis current PIadjustment module and using an output i*_(sd) of a flux linkage currentcommand given module as a command of a d-axis current PI adjustmentmodule; inputting induction motor two-phase currents i_(U) and i_(V)obtained by sampling via a current sensor to a 3-phase staticcoordinate/2-phase static coordinate conversion module, and thenoutputting {right arrow over (i)}_(s) to the 2-phase synchronousrotation coordinate/2-phase static coordinate conversion module, andlastly obtaining a d-axis current i_(sd) and a q-axis current i_(sq) inthe 2-phase synchronous rotation coordinate system, and performing acurrent PI control after using the obtained d-axis current and q-axiscurrent as feedback values of a d-axis current PI regulator and a q-axiscurrent PI regulator respectively and taking a difference withcorresponding flux linkage current commands i*_(sd) and i*_(sq); S504,inputting outputs u_(sd) and u_(sq) of the d-axis and q-axis current PIadjustment modules to the 2-phase synchronous rotationcoordinate/2-phase static coordinate conversion module, which converts amotor input voltage command in the 2-phase synchronous rotationcoordinate system to a motor input voltage command {right arrow over(u)}_(s) in the 2-phase static coordinate system; S505, outputting{right arrow over (u)}_(s) to a voltage space vector pulse widthmodulation module to generate a switching signal capable of controllingswitching devices S_(A), S_(B), S_(C), thereby achieving an object ofcontrolling induction motor speed and torque.
 8. A computer-readablestorage medium, wherein a computer program is stored on thecomputer-readable storage medium, and when the computer program isexecuted by a processor, the virtual voltage injection-based speedsensor-less driving control method for induction motor of claim 1 isimplemented.
 9. The driving control method of claim 2, wherein thevirtual voltage injection module is implemented by an adder, amultiplier, or a combination thereof.
 10. The driving control method ofclaim 2, wherein a calculation formula of the proportional relationshipk in step S1 is as follows: $k = {{p\frac{R_{r}L_{m}}{L_{r}}} + 1}$wherein p is a constant greater than zero, and is obtained based on astability degree of induction motor speed and torque; R_(r) is aninduction motor rotor resistance; L_(m) is an induction motor mutualinductance; and L_(r) is an induction motor rotor side inductance. 11.The driving control method of claim 2, wherein the dynamic mathematicalmodel of the flux linkage observer constructed based on u*_(sα) andu*_(sβ) in step S3 is as follows: $\left\{ {{{\begin{matrix}{{\frac{d}{dt}\hat{\overset{\rightarrow}{x}}} = {{A_{1}\hat{\overset{\rightarrow}{x}}} + {\overset{\rightarrow}{u}}_{s}^{*}}} \\{{\hat{\overset{\rightarrow}{i}}}_{s} = {C\; \hat{\overset{\rightarrow}{x}}}}\end{matrix}{{wherein}:\hat{\overset{\rightarrow}{x}}}} = \begin{bmatrix}{\hat{\lambda}}_{s\; \alpha} & {\hat{\lambda}}_{s\; \beta} & {\hat{\lambda}}_{r\; \alpha} & {\hat{\lambda}}_{r\; \beta}\end{bmatrix}^{T}},{{\overset{\rightarrow}{u}}_{s}^{*} = \begin{bmatrix}u_{s\; \alpha}^{*} & u_{s\; \beta}^{*} & 0 & 0\end{bmatrix}^{T}},{{\hat{\overset{\rightarrow}{i}}}_{s} = \begin{bmatrix}{\hat{i}}_{s\; \alpha} & {\hat{i}}_{s\; \beta}\end{bmatrix}^{T}},{A_{1} = \begin{bmatrix}a_{11} & 0 & a_{13} & 0 \\0 & a_{11} & 0 & a_{13} \\a_{31} & 0 & a_{33} & {- {\hat{\omega}}_{r}} \\0 & a_{31} & {\hat{\omega}}_{r} & a_{33}\end{bmatrix}},{C = {{\begin{bmatrix}h_{1} & 0 & h_{2} & 0 \\0 & h_{1} & 0 & h_{2}\end{bmatrix}a_{11}} = \frac{- R_{s}}{\delta \; L_{s}}}},{a_{13} = \frac{R_{s}L_{m}}{\delta \; L_{s}L_{r}}},{a_{31} = \frac{R_{r}L_{m}}{\delta \; L_{s}L_{r}}},{a_{33} = {{\frac{- R_{r}}{\delta \; L_{r}}h_{1}} = \frac{1}{\delta \; L_{s}}}},{h_{2} = \frac{- L_{m}}{\delta \; L_{s}L_{r}}},{\delta = {1 - \frac{L_{m}^{2}}{L_{s}L_{r}}}}} \right.$the dynamic mathematical model of the flux linkage observer constructedbased on u*_(sd) and u*_(sq) is as follows: $\left\{ {{{\begin{matrix}{{\frac{d}{dt}\hat{\overset{\rightarrow}{x}}} = {{A_{2}\hat{\overset{\rightarrow}{x}}} + {\overset{\rightarrow}{u}}_{s}^{*}}} \\{{\hat{\overset{\rightarrow}{i}}}_{s} = {C\; \hat{\overset{\rightarrow}{x}}}}\end{matrix}{{wherein}:\hat{\overset{\rightarrow}{x}}}} = \begin{bmatrix}{\hat{\lambda}}_{sd} & {\hat{\lambda}}_{sq} & {\hat{\lambda}}_{r\; d} & {\hat{\lambda}}_{rq}\end{bmatrix}^{T}},{{\overset{\rightarrow}{u}}_{s}^{*} = \begin{bmatrix}u_{sd}^{*} & u_{sq}^{*} & 0 & 0\end{bmatrix}^{T}},{{\hat{\overset{\rightarrow}{i}}}_{s} = \begin{bmatrix}{\hat{i}}_{sd} & {\hat{i}}_{sq}\end{bmatrix}^{T}},{A_{1} = \begin{bmatrix}a_{11} & \omega_{e} & a_{13} & 0 \\{- \omega_{e}} & a_{11} & 0 & a_{13} \\a_{31} & 0 & a_{33} & {\omega_{e} - {\hat{\omega}}_{r}} \\0 & a_{31} & {{- \omega_{e}} + {\hat{\omega}}_{r}} & a_{33}\end{bmatrix}},{C = {{\begin{bmatrix}h_{1} & 0 & h_{2} & 0 \\0 & h_{1} & 0 & h_{2}\end{bmatrix}a_{11}} = \frac{- R_{s}}{\delta \; L_{s}}}},{a_{13} = \frac{R_{s}L_{m}}{\delta \; L_{s}L_{r}}},{a_{31} = \frac{R_{r}L_{m}}{\delta \; L_{s}L_{r}}},{a_{33} = {{\frac{- R_{r}}{\delta \; L_{r}}h_{1}} = \frac{1}{\delta \; L_{s}}}},{h_{2} = \frac{- L_{m}}{\delta \; L_{s}L_{r}}},{\delta = {1 - \frac{L_{m}^{2}}{L_{s}L_{r}}}}} \right.$wherein {circumflex over (λ)}_(sα), {circumflex over (λ)}_(sβ),{circumflex over (λ)}_(sd), and {circumflex over (λ)}_(sq) are statorflux linkage observation values under the α-axis, the β-axis, thed-axis, and the q-axis respectively; {circumflex over (λ)}_(rα),{circumflex over (λ)}_(rβ), {circumflex over (λ)}_(rd), and {circumflexover (λ)}_(rq) are rotor flux linkage observation values under theα-axis, the β-axis, the d-axis, and the q-axis respectively; î_(sα),î_(sβ), î_(sd), and î_(sq) are stator current observation values underthe α-axis, the β-axis, the d-axis, and the q-axis respectively; ω_(e)is a synchronous rotating speed; R_(s) and R_(r) are a motor statorresistance and rotor resistance respectively; L_(s), L_(r), and L_(m)are a motor stator side inductance, a motor rotor side inductance, and amotor mutual inductance respectively.
 12. The driving control method ofclaim 2, wherein when the dynamic mathematical model of the flux linkageobserver is constructed based on u*_(sα) and u*_(sβ), a calculationformula of the induction motor rotor speed {circumflex over (ω)}_(r) instep S4 is as follows:{circumflex over (ω)}_(r) =k _(p)[(i _(sα) −î _(sα)){circumflex over(λ)}_(rβ)−(i _(sβ) −î _(sβ)){circumflex over (λ)}_(rα)]+k _(i) S ₁ whenthe dynamic mathematical model of the flux linkage observer isconstructed based on u*_(sd) and u*_(sq), the calculation formula of theinduction motor rotor speed {circumflex over (ω)}_(r) in step S4 is asfollows:{circumflex over (ω)}_(r) =k _(p)[(i _(sd) −î _(sd)){circumflex over(λ)}_(rq)−(i _(sq) −î _(sq)){circumflex over (λ)}_(rd)]+k _(i) S ₂wherein k_(p) and k_(i) are a proportional link gain and an integrallink gain of the rotating speed observer respectively; i_(sα), i_(sβ),i_(sd), and i_(sq) are stator current actual measured values under theα-axis, the β-axis, the d-axis, and the q-axis respectively; {rightarrow over (i)}_(sα), î_(sβ), î_(sd), and î_(sq) are stator currentobservation values under the α-axis, the β-axis, the d-axis, and theq-axis respectively; {circumflex over (λ)}_(rα), {circumflex over(λ)}_(rβ), {circumflex over (λ)}_(rd), and {circumflex over (λ)}_(rq)are rotor flux linkage observation values under the α-axis, the β-axis,the d-axis, and the q-axis respectively; and S₁ and S₂ are time integralvalues of [(i_(sα)−î_(sα)){circumflex over(λ)}_(rβ)−(i_(sβ)−î_(sβ)){circumflex over (λ)}_(rα)] and[(i_(sd)−î_(sd)){circumflex over (λ)}_(rq)−(i_(sq)−î_(sq)){circumflexover (λ)}_(rd)] respectively.
 13. The driving control method of claim 2,wherein when the dynamic mathematical model of the flux linkage observeris constructed based on u*_(sα) and u*_(sβ), a calculation formula ofthe rotation angle {circumflex over (θ)} in step S4 is as follows:$\overset{\hat{}}{\theta} = {\arctan \frac{{\overset{\hat{}}{\lambda}}_{r\beta}}{{\hat{\lambda}}_{r\; \alpha}}}$when the dynamic mathematical model of the flux linkage observer isconstructed based on u*_(sd) and u*_(sq), the calculation formula of therotation angle {circumflex over (θ)} in step S4 is as follows:$\omega_{s} = {\frac{R_{r}L_{m}}{L_{r}{\hat{\lambda}}_{r\; d}}i_{sq}}$$\overset{\hat{}}{\theta} = S_{3}$ wherein {circumflex over (λ)}_(rα),{circumflex over (λ)}_(rβ), and {circumflex over (λ)}_(rd) are rotorflux linkage observation values under the α-axis, the β-axis, and thed-axis respectively; i_(sq) is a stator current actual measured valueunder the q-axis, ω_(s) is a slip rotating speed, R_(r) is a motor rotorresistance, L_(r) and L_(m) are a motor rotor side inductance and amotor mutual inductance respectively, and S₃ represents a time integralfor ({circumflex over (ω)}_(r)+ω_(s)).
 14. The driving control method ofclaim 2, wherein step S5 comprises the following steps: S501, performinga rotating speed PI control after taking a difference with acorresponding rotating speed command ω*_(r) using the observed inductionmotor rotor speed {circumflex over (ω)}_(r) as a feedback value of therotating speed PI adjustment module; S502, using the observed fluxlinkage rotation angle {circumflex over (θ)} for a coordinate conversioncalculation in a 2-phase synchronous rotation coordinate/2-phase staticcoordinate conversion module; S503, using an output i*_(sq) of therotating speed PI adjustment module as a command of a q-axis current PIadjustment module and using an output i*_(sd) of a flux linkage currentcommand given module as a command of a d-axis current PI adjustmentmodule; inputting induction motor two-phase currents i_(U) and i_(V)obtained by sampling via a current sensor to a 3-phase staticcoordinate/2-phase static coordinate conversion module, and thenoutputting {right arrow over (i)}_(s) to the 2-phase synchronousrotation coordinate/2-phase static coordinate conversion module, andlastly obtaining a d-axis current i_(sd) and a q-axis current i_(sq) inthe 2-phase synchronous rotation coordinate system, and performing acurrent PI control after using the obtained d-axis current and q-axiscurrent as feedback values of a d-axis current PI regulator and a q-axiscurrent PI regulator respectively and taking a difference withcorresponding flux linkage current commands i*_(sd) and i*_(sq); S504,inputting outputs u_(sd) and u_(sq) of the d-axis and q-axis current PIadjustment modules to the 2-phase synchronous rotationcoordinate/2-phase static coordinate conversion module, which converts amotor input voltage command in the 2-phase synchronous rotationcoordinate system to a motor input voltage command {right arrow over(u)}_(s) in the 2-phase static coordinate system; S505, outputting{right arrow over (u)}_(s) to a voltage space vector pulse widthmodulation module to generate a switching signal capable of controllingswitching devices S_(A), S_(B), S_(C), thereby achieving an object ofcontrolling induction motor speed and torque.